The main objective of the research is to develop an in vitro system which will synthesize biologically active viruses. The system contains three parts. One is the protein synthesizing system in which a given viral DNA directs messenger RNA synthesis and the synthesized RNA programs the synthesis of proteins (transcription-translation couples system). The second part of the system is a DNA synthesizing system, again a given DNA is the template for the newly synthesized DNA. Finallq, the synthesized viral structural proteins and DNA will be assembled. The system will provide information concerning (1) the fidelity of in vitro systems, (2) control mechanisms of macromolecules in biological systems and (3) assembly process of viral structures.